Reciprocating steam engines were first invented by James Watt who used the property of expansion of gases in conjunction with sliding plate valves to control the path of steam and water squirted into a cylinder to make the steam contract and move a piston. The development of this basic engine led the way to the plethora of steam engines that would power the industrial revolution.
The development of more modern engines began with an engine principle proposed in 1862 by Beau de Rochas, which was later modified by Nicholas Otto and patented in 1876. That contrivance was further developed to become much later the modern Otto engine that is widely used today to power automobiles, ships and planes.
The Otto engine has four strokes in two revolutions of the engine for one sequence cycle that may be either self ignited (diesel) or spark ignited. The strokes are, in order, input stroke, compression stroke, power stroke, and exhaust stroke.
Two stroke engines, used on today's motor bikes, were a later development, and combined the four strokes to occur in one revolution of the engine. A problem with such engines has been that exhaust gases mix with incoming fuel/air gases during the input/compression stroke, and this contamination limits the engine efficiency.
The development of engines was accelerated by the world wars, which led to supercharger Otto engines for planes, jet engines, and liquid fueled engines for rockets. Jet engines and rocket engines produce high output thrust but at a cost of high fuel usage.
The expansion properties of gases have been used to drive all of the aforementioned engines. However, as the world's supply of accessible fossil fuels becomes depleted, and high quality fuels for automobiles becomes more expensive, there is an ever increasing demand for improved output from smaller and more efficient engines.
Although the world's attention is gradually focusing on alternative energy sources to combustible fossil fuels, and there is a desire in some circles to replace engines with electric motors for automobiles, current technology is not at a stage where engines can be replaced with, say, fuel cell or battery powered electric cars. A smaller and more efficient engine using fossil fuels (and especially low grade fuels) to power automobiles, electric generators and other machinery would be a great advantage.
Properly developed rotary engines are ideally placed to serve this purpose. A rotary engine was patented in 1912 using sliding doors in a four stroke emulation of the four stroke Otto reciprocating principle, but in a rotary chamber. There have been many subsequent developments using the same system of partitioning the chamber space, such as by using sliding doors or rotating disc doors to block and unblock the swept chamber space into compartments, thereby emulating the four strokes of the Otto engine.
It is a serious limitation of such rotary engines that the doors are moved whilst there is still pressure within the chamber. The presence of high chamber pressures slows the opening of the doors because of the creation of high frictional loads on the doors. To be most efficient, the doors must be moved very quickly, and this requires lowering the frictional resistance that presently acts upon the doors as they move under high chamber pressures.
It has been found by the present inventor that this limitation can be overcome by providing a rotary engine that is so assembled and operated to release chamber pressure into an exhaust path from the chamber as the piston moves towards the doors but just before the doors begin to be opened.
It is another limitation of prior art rotary engines that their use of cam rollers further reduces their efficiency by increasing the time the doors are in motion, as the cam rollers effectively widen the cam lobes.
There are numerous other limitations of prior art rotary engines which the present inventor has overcome by the present invention.